| 词条 | Simpsonite |
| 释义 |
| name = Simpsonite | category = Oxide minerals | boxwidth = | boxbgcolor = | image = Simpsonite-154999.jpg | imagesize = 300px | caption = Locality: Alto do Giz pegmatite, Rio Grande do Norte, Brazil. Size: 1.6 x 1.5 x 1.8 cm. | formula = Al4(Ta,Nb)3O13(OH) | molweight = 813.65 g/mol | strunz = 4.DC.10 | system = Trigonal | class = Pyramidal (3) H-M symbol: (3) | symmetry = P3 | unit cell = a = 7.37, c = 4.51 [Å]; Z = 1 | color = White to cream, yellow to yellow-brown when altered | habit = Euhedral, prismatic, striated | twinning = | cleavage = None | fracture = Conchoidal | tenacity = Brittle | mohs = 7-7.5 | luster = Vitreous to adamantine | refractive = nω = 2.045 nε = 2.025 | opticalprop = Uniaxial negative | birefringence = δ = 0.020 | pleochroism = | streak = White | gravity = 6.7 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Semitransparent | other = Blue-white cathodoluminescence and yellow fluorescence in SW UV | references = [1][2][3][4] }} Simpsonite has a general formula of Al4(Ta,Nb)3O13(OH). It occurs as euhedral to subhedral tabular to short and prismatic crystals, commonly in subparallel groups. Under the petrographic microscope it has a very high relief. Discovered in 1938, it was named after Edward Sydney Simpson (1875–1939), government mineralogist and analyst of Western Australia.[3] It is an accessory mineral in some tantalum-rich granite pegmatites. It occurs in association with tantalite, manganotantalite, microlite, tapiolite, beryl, spodumene, montebrasite, pollucite, petalite, eucryptite, tourmaline, muscovite and quartz.[1] It is found in a few locations around the world, notably in the Onca and Paraiba mines of Rio Grande do Norte, Brazil and at Tabba Tabba, Western Australia.[1] References1. ^1 2 Handbook of Mineralogy {{Commons category}}2. ^Webmineral data 3. ^1 Simpsonite: Mindat.org 4. ^Philonen, P.C., Grew, E.S., Ercit, T.S., Roberts, A.C., Jambor, J.L. (2005) New mineral names. American Mineralogist, 90, 1227-1233 5 : Aluminium minerals|Oxide minerals|Tantalum minerals|Niobium minerals|Trigonal minerals |
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